1. Field of the Invention
The present invention relates to electrical sockets, and particularly to an electrical socket having terminals with resilient mating beams.
2. Description of the Prior Art
With the trend toward miniaturization in computer technology, land grid array (LGA) electrical sockets are becoming smaller and smaller. The LGA socket mainly comprises an insulative housing and a multiplicity of terminals. Due to the small size of the terminals, mating beams thereof are easily damaged because of large stress produced therein when the terminals are engaged with electrodes of a complementary electronic package such as a central processing unit (CPU). Several solutions have been developed to overcome this problem. One solution is disclosed in U.S. Pat. Nos. 6,315,576 and 6,290,507. The structure of the terminals is modified so as to obtain optimal electrical and mechanical performance of the mating beams of the terminals. Another solution is disclosed in U.S. Pat. Nos. 6,186,797 and 6,132,220. The arrangement of the terminals with respect to a base of an insulative housing of the socket is modified. In an electrical socket as disclosed in U.S. Pat. No. 6,186,797, a base plate of the socket defines an array of terminal holes arranged in a lattice-like array for receiving corresponding terminals therein. Respective rows of the terminal holes are oriented at a same angle, preferably 45 degrees, with respect to sides of the base plate. In this way, not only is miniaturization of the pitch of adjacent terminals enhanced, but also the performance of the terminals is improved. However, the terminals cannot be fitted into the lattice-shaped terminal holes of the base plate simultaneously, due to the limitations of existing manufacturing technology for the terminals. Thus assembly of the terminals is unduly complicated. Furthermore, in forming the terminal holes oriented at 45 degrees, core pins of the base plate mold also need to be oriented at 45 degrees. This complicates formation of the base plate mold.
Therefore, it would be very beneficial to provide an electrical socket having terminals which reliably electrically connect with electrodes of an electronic package, and which allows easy assembly of the terminals into terminal holes of the electrical socket.
Accordingly, a main object of the present invention is to provide an electrical socket having conductive terminals, wherein the terminals enhance the performance of the socket while still maintaining a high density array in the socket.
To fulfill the above-mentioned object, an electrical socket for connecting an LGA chip with a PCB is provided by the present invention. In a preferred embodiment, the electrical socket includes an insulative housing having a plurality of passageways extending therethrough, and a plurality of terminals assembled in the corresponding passageways of the housing. Each terminal includes a locating plate arranged in rows, and a mating beam connected to the locating plate and extending along the corresponding row. The terminals and the mating beams are arranged so that a projection of each mating beam along the corresponding row is longer than a distance between each two adjacent locating plates of two adjacent terminals arranged in the same row. Accordingly, when the mating beams are engaged with electrodes of the LGA chip, the mating beams are long enough to provide excellent resilient deflection characteristics, thereby ensuring good mechanical and electrical connection between the mating beams and the electrodes.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: